1. Technical Field
This invention relates to transmission brakes for vehicles in which the transmission is held in place by engaging both drive and reverse gears simultaneously allowing the engine to be accelerated without moving the vehicle until the reverse gear is released. Such devices are used in high performance automobile drag racing in which it is important to get the fastest start possible when utilizing an automatic electronic controlled transmission.
2. Description of Prior Art
Prior art devices of this type have been directed to a variety of ways in which automatic transmissions can be selectively locked into a braking position for drag racing purposes when released, see for example U.S. Pat. Nos. 4,883,151, 5,148,720, 5,622,088 and 6,050,384.
In U.S. Pat. No. 4,883,151 a transmission brake is disclosed for automatic transmissions in which the conventional gear selector is modified in the vehicle with two gear engagement positions by modifying the existing manual selecting switch shift valve.
U.S. Pat. No. 5,148,720 discloses a lock-up solenoid assembly that is universal that closes off a fluid passageway allowing pressure to build up in a control chamber moving a valve element so that the front portion of the torque converter can empty itself, effectively locking the transmission.
An automatic transmission for racing is set forth in U.S. Pat. No. 5,622,088 which has a reverse gear piston that is engageable to act as a transmission brake.
U.S. Pat. No. 6,050,384 is directed to a method and device for rapid transmission brake release in which a modification to the automatic transmission is made applicable to Turbo Hydromatic 400 Transmissions. A pressure release passageway is provided in the servo cover so that it can be selectively blocked and unblocked by a solenoid.